[ovirt-users] Updating nodes

[Itamar Heim]

On 05/12/2014 12:43 AM, Paul Heinlein wrote:
> On Sun, 11 May 2014, Itamar Heim wrote:
>
>>>  I just inherited an oVirt cluster at work that's running 3.2 on
>>>  Fedora 18 and would dearly love some direction about updating
>>>  things without a system-wide downtime.
>>
>> 1. no downtime should happen, as you can upgrade hosts by moving
>>    them to maintenance, which will live migrate VMs running on them.
>>
>> 2. fedora 18 is EOL, so 'yum update' isn't going to help here.
>>
>> 3. re-install host should refresh vdsm and its dependent packages if
>>    the repo's configured have newer versions. when the host is in
>>    maint, you can simply run 'yum update' on the host, then
>>    re-activate it (of course reboot if kernel got updated, etc.)
>
> I've followed those steps, and I can get VMs migrated *to* the updated
> nodes. I have two worries:
>
>   1. VMs migrated to the updated nodes cannot be migrated back to the
>      old nodes. So once I start, it's all-in or nothing. Is that to be
>      expected?

on fedora hosts this can happen, since there is no live migration 
compatibility between fedora versions.
on .el6 hosts this shouldn't happen[1]

>
>   2. Once all the nodes are backed up, is there a fairly sure-fire way
>      to update the master engine? Is that documented somewhere?

a. you should be able to upgrade engine or hosts regardless of each
    other.
b. the setup (upgrade) script takes a db backup just in case. if you
    happen to run it in a VM, snapshot/backing it up doesn't hurt as
    well.
c. if upgrading to a new minor version, note to change in the upgraded
    engine the cluster and DC level to benefit from new features.


>
> Thanks!
>

[1] there is a known caveat is you have selinux disabled on some 
machines and enabled on others.